Dual-lumen catheters have come into widespread use for extracorporeal blood purification procedures such as hemodialysis. Blood is withdrawn from the patient through one of the lumens of the catheter and supplied to a hemodialysis unit where the blood is purified, and the resulting purified blood is then returned to the patient through the other lumen of the catheter. Examples of such catheters are shown in U.S. Pat. Nos. 4,134,402; 4,583,968; and 4,682,978.
Although these catheters were originally intended for acute hemodialysis treatments, the catheters have proven to be so satisfactory that they are typically allowed to remain in patients for several weeks, and sometimes for several months. The catheters are used for the hemodialysis treatments that such patients receive approximately every three days, and during the interdialytic periods the catheter remains inserted in and attached to the patient.
Dual-lumen hemodialysis catheters are normally supplied with certain auxiliary components permanently pre-attached to the catheter. These auxiliary components facilitate the connection of the two lumens of the catheter (which are extremely small within the catheter) to a pair of long flexible tubes which carry blood to and from the hemodialysis unit. The auxiliary components include a Y-shaped hub which receives the proximal end of the catheter at one end of the hub, and a pair of extension tubes which are fastened to the opposite end of the hub and carry a pair of clamps, female luer fittings for connection to male luer fittings on the long tubes leading to the hemodialysis unit, and a pair of caps (usually with injectable elastomeric ports) closing the openings of the luer fittings.
The hub and portions of the extension tubes affixed to the catheter are normally used to secure the catheter to the patient, by the use of sutures and by applying tape or an adhesive-coated bandage across the hub and/or the extension tubes and adhering the tape or bandage to the skin of the patient on opposite sides of the hub. Sometimes the hub forms either a suture groove or a suture web or "wing" to facilitate attachment to the patient by suturing. Because of the length of the extension tubes and the other auxiliary components, the extracorporeal part of the catheter assembly usually extends beyond the patient's body. As a result, the catheter is continually disturbed by movements of the patient and/or people and equipment around the patient, or by clothing which is periodically donned or removed by the patient. It is not unusual for such movements to cause the catheter to become dislodged entirely from the patient. Even when the catheter is not dislodged, continual movement of the catheter within the vein causes discomfort and pain to the patient, and can lead to damage to the vein in which the catheter is inserted.
For example, when the catheter is inserted in a jugular vein, the extension tubes normally extend upwardly along the neck and ear of the patient. This not only makes it difficult to attach the catheter to the patient (sometimes the hub or extension tubes are taped to the ear or even around the entire neck or head of the patient), but also places both the hub and the extension tubes in the direct path of movement of the patient's head. When the catheter is inserted into a subclavian vein, which is located under the clavicle, the extension tubes typically project upwardly or outwardly beyond the shoulder of the patient.
Regardless of where the catheter is located on the patient's body, the weight of the long tubes leading to the dialysis unit, which typically have a larger cross section than the extension tubes, often exerts pulling forces on the extension tubes and the catheter, which of course tends to withdraw the catheter from the patient's body. These forces are also applied to the sutures, causing discomfort and pain to the patient, and can cause the catheter to pivot back and forth within the vein, thereby irritating the walls of the vein. Such catheter movements can also cause suction forces to be exerted on the vein walls.